The present invention relates to the support of clutch assemblies, in particular, to outwardly supporting motorcycle clutch assemblies.
A typical clutch assembly incorporates a rotating clutch disk plate selectively secured against a facing plate. This facing plate is directly secured to the fly wheel. The clutch disk plate is connected via a spline to the mainshaft, which extends in opposite directions and thru both plates. One end of the mainshaft goes thru the clutch disk plate and into the transmission. The other end goes thru the facing plate, the flywheel and on into the crankshaft of the engine. There is a support bearing near each of the plates to support the mainshaft and accurately position the clutch disk plate. However, certain manufacturers of motorcycles have elected to place the clutch assemblies so that they are supported with only a single bearing on the inward side, providing only limited support to the entire clutch assembly and transmission input shaft or mainshaft.
Typically a motorcycle xe2x80x9cwetxe2x80x9d clutch assembly is composed of an adjusting plate, spring assembly, pressure plate, adjusting screw, disk assembly, inner hub, outer hub, pilot bearing, and transmission input shaft or mainshaft. The disk assembly consists of 6-8 fiber disks xe2x80x9cstackedxe2x80x9d in a parallel arrangement along a common axis between parallel metal plates. The disk assembly is connected to the inner hub via splines on the metal disks. The disk assembly is connected to the outer hub via extended legs on the fiber disks. The clutch is released or disengaged by the push rod exerting force on the pressure plate, which is permitted to move outwardly, by compressing the spring assembly. The spring assembly being fixed outwardly by the adjusting plate, which is secured via bolts to the inner hub. The amount of compression being determined by the positioning of this adjustment plate relative to the bosses on the inner hub. Different positionings being determined by shims or an adjustment capability built into the adjustment plate itself. Disengagement permits the inner hub to move freely of the outer hub and rotate freely on the pilot. bearing. The inner hub is directly connected to the end of the transmission input shaft via a keyway and nut. The mainshaft then proceeds inwardly thru the pilot bearing in the outer hub, then thru an inward support bearing and subsequently into the interior of the transmission output shaft and subsequently into the transmission. The outer hub is connected to the engine by a chain or belt which attaches to the drive sprocket on the outer hub. The disengagement of the rotation of the outer hub from the inner hub is what achieves the disengagement of the motor from the transmission. However, the entire clutch assembly is outwardly positioned from the inward support bearing, its only means of support.
The energy from the engine is typically supplied by a chain drive which pulls the entire. clutch assembly forward. This forward movement, of the entire clutch assembly, presses the transmission input shaft against one side of the inward support bearing, causing rapid wear. This forward movement of the clutch also causes misalignment of the clutch release elements and consequently the clutch is no longer able to be fully disengaged. Without proper disengagement of the clutch, shifting up or down cannot be done without grinding of gears, clanking, or other difficulties since the clutch is now binding or dragging when it should be completely disengaged. The forward movement of the clutch assembly also causes unnecessary transmission wear. The transmission input shaft passes thru the transmission output shaft and on into the transmission. Any misalignment or binding of these two shafts causes premature wearing of these shafts and reduces the overall power output of the motorcycle. As the transmission input shaft enters into the transmission, its misalignment will also affect any gears, bushings, and bearings which it impacts upon. All of these problems, caused by the forward movement of the clutch assembly, are exacerbated as wear occurs and accumulates on the inward support bearing.
A further problem is looseness in the linkage between the rear (drive) wheel and the engine, commonly called xe2x80x9cbacklash.xe2x80x9d A certain amount of backlash is necessary. However, it is desirable to minimize this looseness as much as possible. Fore and aft motion of the clutch relative to the engine and the rear wheel provide a significant component of motorcycle drive train backlash. An unstabilized clutch assembly significantly contributes to the drive train backlash.
An additional problem in certain motorcycle models is starter drive inefficiency. The motorcycle starter drive engages the ring gear of the outer hub of the clutch which also is connected via the drive sprocket to the engine via chain or belt drive. If the motorcycle is started while in neutral, the starter drive will force the clutch assembly away from the starter drive and cause a binding of the gears in the starter drive and ring gear. If the motorcycle is started while in gear, the engagement of the outer hub by the starter drive, again urges the clutch to move away from the starter drive, causing the clutch to partially engage, increasing the energy needed to start the motorcycle engine.
The present invention provides several embodiments of clutch assembly outboard supports comprising at least one bearing mounted to an outer structure near the clutch assembly, e.g. the clutch housing or protective cover, and mounted to or impacting upon the clutch assembly itself, to relieve the force applied upon the inward support bearing and to restrict clutch assembly motion regardless of the engine, starter drive or other forces applied to it. The embodiments according to the present invention substantially enhance the bearing life and increase the positional stability of the clutch assembly in its normal operation without disturbing traditional outboard clutch deployment. Furthermore, the increased clutch stability and alignment according to the present invention provide more complete clutch disengagement allowing for significantly improved transmission shifting characteristics by reducing or eliminating clutch drag during shifting. Furthermore, these embodiments according to the present invention reduce wear on the transmission and starter assemblies, provide increased starter efficiency, reduce drive line backlash, and potentially enhance performance by increasing available power.